special powder chambers to test the pressure, etc., of
confined explosives. The experience thus gained enabled the construction
of the instrument here shown, which is adapted to direct attachment to
the gun, making it as easy now to measure gunpowder pressures as it had
been, heretofore, to measure steam pressures. The effect of this movement
is to reduce the exaggerated statement of high pressures, obtained from
ordinary sporting powders; these have been accredited with pressures up
to 40,000 lb. per square inch, but they only really gave 22,000 lb. by
actual gauge measurement. Artillerists and ordnance officers have, in
this instrument, a true pulse of the internal pressures of the gun, of
inestimable value when determining the quantity of powder and the proper
weight of shot. These are important matters in ordnance practice.

This gauge is a compact machine, designed to measure and indicate the
quick pressures resulting from gunpowder explosives and the slow
pressures of hydraulic force; the same mechanism used in both cases
permits the ready testing and examination of gauge under hydraulic
pressure, to determine its accuracy, for the more sudden pressure
occasioned by the use of gunpowder.

* * * * *

IMPROVED PLAITING MACHINE.

The principal object the inventors of the machine we illustrate herewith
had in view in designing it was to arrange a mode of working the grip
motion positively, so that the cloth shall be received freely and without
strain or friction before or up to the very instant at which each fold is
completed, and shall then be seized and firmly held. In existing machines
there is not we believe, any arrangement for the accomplishment of this
purpose; it is true, the table upon which the cloth is folded is relieved
at the termination of the stroke of the plaiting knife, but the upper
gripper bar, against which the folds of cloth are pressed upon the return
of the table to its normal position, is stationary, being rigidly fixed
to the sides of the machine. One result of this rigidity is that the
cloth has to be forcibly thrust by the plaiting knife under the upper
gripper bar, and in consequence of the violence involved the fold just
made at the opposite end is dragged out from the grip, making a short
fold, and further, in the case of delicate finishes, giving rise to
damaged goods. Another result of this arrangement, when the cloth is not
pressed against the